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• 1. [Article] Riparian Shade Assessment and Restoration Priorities Analysis in the Damascus Urban Growth Boundary Expansion Area

  An important component of progressive urban planning is the protection and restoration of riparian environments, particularly in the Pacific Northwest where increasing stream temperatures threaten the ...

  Citation × Citation Citation Abstract Copy Title: Riparian Shade Assessment and Restoration Priorities Analysis in the Damascus Urban Growth Boundary Expansion Area Author: Leferink, Robin K. Year: 2007 An important component of progressive urban planning is the protection and restoration of riparian environments, particularly in the Pacific Northwest where increasing stream temperatures threaten the survival of endangered salmonids and other cold-water biota. Restoration projects are often led by watershed councils or other grassroots organizations with limited resources, and it is essential that these groups have an efficient and effective approach to determine priority areas where their efforts can be directed to achieve the greatest ecological benefit. The purpose of this project was to quantify existing riparian shade levels and identify priority reaches for shade restoration on Clackamas River basin streams in the Damascus area expansion of the Portland, Oregon urban growth boundary. Additionally, potential errors in the Metro Regional Land Information System (RLIS) Lite geographic information system (GIS) coverage of the area’s streams were identified and corrected where possible. Riparian shade levels were quantified through interpretation of digital aerial photographs using GIS. At the start of the shade analysis six 50 m reaches in the study area were surveyed using a spherical densiometer to calibrate the aerial photo interpretation. Following the analysis, the method accuracy was assessed by comparing GIS-derived shade classes with field data from 25 sites in the study area that were surveyed in 2003. Stream reaches were identified and prioritized for restoration based on riparian shade level, presence or absence of late-summer flow (as determined through field investigations), and GISevaluated stream aspect (i.e. the direction of stream flow). Generally, the headwaters were found to have less shade than the downstream areas and many of the headwater reaches were identified as the highest restoration priority. Of the 60.5 km of streams assessed in the riparian shade analysis, 24.7 km were identified as potential restoration reaches based on shade levels and late-summer flow conditions. These 24.7 km were further broken into five priority ranks, with 4.1 km of stream reaches assigned to the highest shade restoration priority class. Potential errors in the GIS stream coverage were identified in conjunction with the riparian shade assessment. Where possible, these errors were corrected based on the aerial photographs. Although in many cases access was limited, a total of 18 site visits were made to verify stream locations. The results of this watershed-scale restoration priorities analysis are being used by Clackamas River Basin Council and others to guide restoration planning in the new urban area. While focusing on the high priority stream reaches identified, restoration managers will also need to consider reach-scale factors including land use plans, riparian continuity, parcel size, and landowner cooperation in the final selection of restoration sites. The GIS stream layer corrections were provided to Metro and to the City of Damascus for use in their 2007 natural resource inventory. Title: Riparian Shade Assessment and Restoration Priorities Analysis in the Damascus Urban Growth Boundary Expansion Area Author: Leferink, Robin K. Year: 2007 An important component of progressive urban planning is the protection and restoration of riparian environments, particularly in the Pacific Northwest where increasing stream temperatures threaten the survival of endangered salmonids and other cold-water biota. Restoration projects are often led by watershed councils or other grassroots organizations with limited resources, and it is essential that these groups have an efficient and effective approach to determine priority areas where their efforts can be directed to achieve the greatest ecological benefit. The purpose of this project was to quantify existing riparian shade levels and identify priority reaches for shade restoration on Clackamas River basin streams in the Damascus area expansion of the Portland, Oregon urban growth boundary. Additionally, potential errors in the Metro Regional Land Information System (RLIS) Lite geographic information system (GIS) coverage of the area’s streams were identified and corrected where possible. Riparian shade levels were quantified through interpretation of digital aerial photographs using GIS. At the start of the shade analysis six 50 m reaches in the study area were surveyed using a spherical densiometer to calibrate the aerial photo interpretation. Following the analysis, the method accuracy was assessed by comparing GIS-derived shade classes with field data from 25 sites in the study area that were surveyed in 2003. Stream reaches were identified and prioritized for restoration based on riparian shade level, presence or absence of late-summer flow (as determined through field investigations), and GISevaluated stream aspect (i.e. the direction of stream flow). Generally, the headwaters were found to have less shade than the downstream areas and many of the headwater reaches were identified as the highest restoration priority. Of the 60.5 km of streams assessed in the riparian shade analysis, 24.7 km were identified as potential restoration reaches based on shade levels and late-summer flow conditions. These 24.7 km were further broken into five priority ranks, with 4.1 km of stream reaches assigned to the highest shade restoration priority class. Potential errors in the GIS stream coverage were identified in conjunction with the riparian shade assessment. Where possible, these errors were corrected based on the aerial photographs. Although in many cases access was limited, a total of 18 site visits were made to verify stream locations. The results of this watershed-scale restoration priorities analysis are being used by Clackamas River Basin Council and others to guide restoration planning in the new urban area. While focusing on the high priority stream reaches identified, restoration managers will also need to consider reach-scale factors including land use plans, riparian continuity, parcel size, and landowner cooperation in the final selection of restoration sites. The GIS stream layer corrections were provided to Metro and to the City of Damascus for use in their 2007 natural resource inventory. Close

• 2. [Article] The Influence of Floodplain Restoration on Flow and Sediment Dynamics in an Urban River

  A study of floodplain sedimentation on a recently restored floodplain is presented. This study uses a two-dimensional hydro-morphodynamic model for predicting flow and suspended-sediment dynamics in the ...

  Citation × Citation Citation Abstract Copy Title: The Influence of Floodplain Restoration on Flow and Sediment Dynamics in an Urban River Author: Ahilan, Sangaralingam, Guan, Mingfu, Sleigh, Andrew, Wright, Nigel G., Chang, Heejun Year: 2016 A study of floodplain sedimentation on a recently restored floodplain is presented. This study uses a two-dimensional hydro-morphodynamic model for predicting flow and suspended-sediment dynamics in the downstream of Johnson Creek, the East Lents reach, where the bank of the river has been reconfigured to reconnect to a restored floodplain on a 0.26 km2 (26-ha) site. The simulation scenarios include 10-, 50-, 100- and 500-year event-based deposition modelling of flood events and long-term modelling using the 64 historical flood events between 1941 and 2014. Simulation results showed that the restored floodplain significantly attenuates the upstream flood peak by up to 25% at the downstream. Results also indicated that approximately 20%–30% of sediment from the upstream is deposited on the East Lents floodplain. Furthermore, deposited sediment over the simulated period (1941–2014) is approximately 0.1% of the basin's flood storage capacity; however, the reduction in the storage does not offset the overall flood resilience impact of the flood basin. The sediment conservation at the East Lents flood basin as predicted by the model reduces the annual sediment loading of the Johnson Creek by 1% at the confluence with Willamette River, providing both improved water quality and flood resilience further downstream. Title: The Influence of Floodplain Restoration on Flow and Sediment Dynamics in an Urban River Author: Ahilan, Sangaralingam, Guan, Mingfu, Sleigh, Andrew, Wright, Nigel G., Chang, Heejun Year: 2016 A study of floodplain sedimentation on a recently restored floodplain is presented. This study uses a two-dimensional hydro-morphodynamic model for predicting flow and suspended-sediment dynamics in the downstream of Johnson Creek, the East Lents reach, where the bank of the river has been reconfigured to reconnect to a restored floodplain on a 0.26 km2 (26-ha) site. The simulation scenarios include 10-, 50-, 100- and 500-year event-based deposition modelling of flood events and long-term modelling using the 64 historical flood events between 1941 and 2014. Simulation results showed that the restored floodplain significantly attenuates the upstream flood peak by up to 25% at the downstream. Results also indicated that approximately 20%–30% of sediment from the upstream is deposited on the East Lents floodplain. Furthermore, deposited sediment over the simulated period (1941–2014) is approximately 0.1% of the basin's flood storage capacity; however, the reduction in the storage does not offset the overall flood resilience impact of the flood basin. The sediment conservation at the East Lents flood basin as predicted by the model reduces the annual sediment loading of the Johnson Creek by 1% at the confluence with Willamette River, providing both improved water quality and flood resilience further downstream. Close